Method of ion beam milling a glass substrate prior to depositing a coating system thereon, and corresponding system for carrying out the same

ABSTRACT

A glass substrate is ion beam milled in order to smoothen the same and/or reduce or remove nano-cracks in the substrate surface before a coating system (e.g., diamond-like carbon (DLC) inclusive coating system) is deposited thereon. It has been found that such ion beam milling of the substrate prior to deposition of the coating system improves adherence of the coating system to the underlying milled substrate. Moreover, it has surprisingly been found that such ion beam milling of the substrate results in a more scratch resistant coated article when a DLC inclusive coating system is thereafter ion beam deposited on the milled substrate. Amounts sodium (Na) may also be reduced at the surface of the substrate by such milling.

This application is a CON OF Ser. No. 09/703,709, filed Nov. 2, 2000,now U.S. Pat. No. 6,368,664; which is a CIP OF Ser. No. 09/657,132,filed Sep. 7, 2000, now U.S. Pat. No. 6,277,480, which is a CIP OF Ser.No. 09/627,441, filed Jul. 28, 2000, now U.S. Pat. No. 6,280,834, and aCIP OF Ser. No. 09/617,815, filed Jul. 17, 2000, now U.S. Pat. No.6,312,808, and a CIP OF Ser. No. 09/303,548, filed May 3, 1999, now U.S.Pat. No. 6,261,693, and a CIP OF Ser. No. 09/442,805, filed Nov. 18,1999, now U.S. Pat. No. 6,338,901, and a CIP OF Ser. No. 09/583,862,filed Jun. 1, 2000, now U.S. Pat. No. 6,335,086, the entire contents ofwhich are hereby incorporated by reference in this application.

BACKGROUND OF THE INVENTION

This invention relates to a method and system for ion beam milling aglass substrate prior to depositing a coating system (e.g., diamond-likecarbon (DLC) inclusive coating system) thereon.

Each of the aforesaid parent applications relates to a DLC inclusivecoating system on a substrate. Certain embodiments of certain of theparent applications relate to hydrophobic DLC inclusive coating systemswhere it is desirable to deposit a coating system having a high initialcontact angle θ.

Each of the coating systems disclosed in the aforesaid parentapplications is excellent and works in an efficient manner. However, thecoating systems may be improved by increasing their adherence to theunderlying substrate. Moreover, it would also be beneficial to increasethe scratch resistance of such coating systems.

Thus, it will be appreciated by those skilled in the art that thereexists a need(s) in the art for a method of manufacturing any of thecoating systems in the aforesaid parent applications (or any othersuitable coating system) in a manner so as to improve adherence to theunderlying substrate and/or to make the resulting coated article morescratch resistant. It is a purpose of different embodiments of thisinvention to fulfill one or more of the above described needs in theart, and/or other needs which will become apparent to the skilledartisan once given the following disclosure.

SUMMARY OF THE INVENTION

According to exemplary embodiments of this invention, a glass substrateis ion beam milled prior to deposition of a coating system (e.g.,diamond-like carbon (DLC) inclusive coating system) thereon. Ion beammilling functions to remove or shave off a portion of the glasssubstrate in order to smoothen a surface of the substrate and/orremove/reduce nano-cracks which may have been present in the originalsubstrate surface. Following the ion beam milling, the coating system isdeposited on the smoothened surface of the substrate (e.g., via ion beamdeposition, sputtering or the like).

According to certain exemplary embodiments of this invention, ion beammilling of a substrate prior to deposition of a coating system thereonenables resulting coating systems when deposited to better adhere to thesubstrate. Moreover, with respect to DLC inclusive coating systems, ithas surprisingly been found that such ion beam milling results in thecoated article having improved scratch resistance. Ion beam milling mayalso function to reduce sodium (Na) content adjacent a milled surface ofa soda inclusive glass substrate (e.g., soda-lime-silica glasssubstrate), thereby reducing the potential for sodium induced corrosionon the resulting coated article.

Coated articles made according to certain embodiments of this inventionmay be hydrophobic (e.g., shed water) or non-hydrophobic in differentembodiments. In hydrophobic embodiments, an object of this invention isto provide a durable coated article that can shed or repel water (e.g.automotive windshield, automotive backlite, automotive side window,architectural window, bathroom shower glass, residential window,bathroom shower door, coated ceramic article/tile, etc.).

The hydrophobic nature of such articles is often characterized byrelatively high initial contact angles θ. For example, coated articlesherein may be characterized by an initial contact angle θ (i.e. prior tobeing exposed to environmental tests, rubbing tests, acid tests, UVtests, or the like) of at least about 55 degrees, more preferably of atleast about 80 degrees, even more preferably of at least about 100degrees and most preferably of at least about 110 degrees.

The instant ion beam milling invention may be used in conjunction withvarious types of DLC inclusive layer systems and other types ofcoating/layer systems, and is not intended to be limiting in thatregard.

Generally speaking, certain exemplary embodiments of this invention seekto fulfill one or more of the above-listed needs in the art by providinga method of making a coated article comprising the steps of:

providing a substrate;

ion beam milling substantially an entire surface of the substrate so asto thin the substrate and smoothen the surface of the substrate; and

depositing a coating system on at least a portion of the ion beam milledsurface of the substrate following said ion beam milling step so as toform the coated article.

In certain embodiments, the method of claim 27, wherein said ion beammilling step is performed in a manner so as to increase scratchresistance (SR) of the coated article by at least a factor of two,and/or so that an average surface roughness of the ion beam milledsurface of the substrate following said ion beam milling is no more thanabout 80% of what an average surface roughness of the surface of thesubstrate was prior to said ion beam milling.

In certain embodiments, the depositing step comprises ion beamdepositing at least one DLC inclusive layer on the ion beam milledsurface of the substrate.

Certain exemplary embodiments of this invention further fulfill one ormore of the above-listed needs by providing a coated article comprising:

an ion beam milled glass substrate; and

a coating system including at least one layer deposited on an ion beammilled surface of said glass substrate.

This invention will now be described with respect to certain embodimentsthereof, along with reference to the accompanying illustrations.

IN THE DRAWINGS

FIG. 1 is a flowchart illustrating certain steps taken in accordancewith an embodiment of this invention.

FIG. 2 is a side cross sectional view of a portion of a glass substrateprior to ion beam milling.

FIG. 3 is a side cross sectional view of the portion of the glasssubstrate of FIG. 2 after ion beam milling according to an embodiment ofthis invention has been performed (it is noted that the surface of thesubstrate to receive a coating system thereon has been smoothed by themilling, and certain nano-cracks have been removed).

FIG. 4(a) is a schematic diagram from a side view perspectiveillustrating ion beam milling of a glass substrate according to anembodiment of this invention.

FIG. 4(b) is a top view of the diagram of FIG. 4(a).

FIG. 5(a) is a surface roughness versus number of ion beam passes graphillustrating that a greater number of ion beam milling passes smoothensa substrate surface more than a fewer number of such passes.

FIG. 5(b) is a scratch resistance versus number of ion beam millingscans graph illustrating that scratch resistance of a tempered coatedarticle improves as a function of ion beam milling scans over theunderlying substrate prior to deposition of the coating system thereon.

FIG. 5(c) is a scratch resistance versus number of ion beam millingscans graph illustrating that scratch resistance of an annealed coatedarticle improves as a function of ion beam milling scans over theunderlying substrate prior to deposition of the coating system thereon.

FIG. 6(a) is a schematic side cross sectional view illustratingexemplary gases used in depositing a plurality of layers on a substrateafter the ion beam milling of FIGS. 1-5 has been performed in accordancewith an exemplary embodiment of this invention.

FIG. 6(b) is a side cross sectional view of a coated article resultingfrom the use of the gases of FIG. 6(a) during the article manufacturingprocess.

FIG. 6(c) is a side cross sectional view of a coated article accordingto another embodiment of this invention, that is similar to theembodiment of FIGS. 6(a)-(b) except that layers 4 and 6 are not includedin this embodiment.

FIG. 6(d) is a side cross sectional view of a coated article accordingto another embodiment of this invention, similar to the embodiments ofFIGS. 6(a)-(b) except that layers 2, 4 and 6 are not included in thisembodiment.

FIG. 6(e) is a side cross sectional view of a coated article accordingto yet another embodiment of this invention, similar to the embodimentsof FIGS. 6(a)-(b) except that layers 2 and 4 are not included in thisembodiment.

FIG. 7 is a side cross sectional view of a coated article according toanother embodiment of this invention, wherein after the ion beam millingof the underlying substrate has been performed as in FIGS. 1-5, DLC andFAS inclusive coating(s) or coating system of FIG. 6(b) is/are providedover an intermediate layer(s).

FIG. 8 is a side cross sectional view of a coated article according toanother embodiment of this invention.

FIG. 9(a) is a side cross sectional partially schematic viewillustrating a low contact angle θ of a water drop on a glass substrate.

FIG. 9(b) is a side cross sectional partially schematic viewillustrating the coated article of any of the FIGS. 6-8 embodiments ofthis invention and the contact angle θ of a water drop thereon (inembodiments where hydrophobicity is desired).

FIG. 10 is a perspective view of a linear ion beam source which may beused in any embodiment of this invention for ion beam milling a glasssubstrate or for depositing DLC inclusive layer(s) and/or siloxanegas-deposited layer(s).

FIG. 11 is a cross sectional view of the linear ion beam source of FIG.10.

FIG. 12 is a diagram illustrating tilt angle as discussed herein inaccordance with certain embodiments of this invention.

FIG. 13 is a flowchart illustrating certain steps taken according toexemplary embodiments where an optional FAS inclusive hydrophobic layeris thermally cured after being deposited on the ion beam milledsubstrate over at least one DLC inclusive layer.

FIG. 14 illustrates a chemical structure of exemplary HMDSO.

FIG. 15 illustrates a chemical structure of exemplary DMS.

FIG. 16 illustrates a chemical structure of exemplary TMS.

FIG. 17 illustrates a chemical structure of exemplary 3MS.

FIG. 18 illustrates a chemical structure of exemplary OMCTSO.

FIG. 19 illustrates a chemical structure of exemplary TMDSO.

FIG. 20 illustrates a chemical structure of exemplary TEOS.

FIG. 21 is a flowchart illustrating certain steps taken in accordancewith an embodiment of this invention where the substrate is heated priorto or during ion beam deposition of a DLC inclusive layer(s) so as tomake the resulting coating system more durable and/or more resistant tolosing significant amounts of its original hydrophobic nature (suchheating of the substrate may occur either before, during, and/or afterthe ion beam milling of FIGS. 1-5).

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THIS INVENTION

Referring now more particularly to the accompanying drawings in whichlike reference numerals indicate like elements throughout theaccompanying views.

FIG. 1 is a flowchart illustrating certain steps taken in accordancewith an embodiment of this invention. First, in step 100, a glasssubstrate 1 is provided. The glass substrate may be from about 1-6 mmthick, more preferably from about 1.5 to 4.0 mm thick. Soda-lime-silicaglass is preferred for the substrate, although other types of glass suchas borosilicate glass may instead be used. The glass substrate 1 may betempered or annealed in different embodiments of this invention.

FIG. 2 is a side cross sectional view of a typical glass substrate 1that is provided in step 100. As can be seen, a first major surface 105of glass substrate 1 has a rather roughened surface, and also includesnano-cracks 106 defined therein. It has been found that the presence ofthe nano-cracks and surface roughness may adversely affect the adherenceof a coating system to the surface 105 of the substrate 1.

Referring back to FIG. 1, in step 101 the entire surface 105 of glasssubstrate 1 is then passed under one or more linear ion beam sources(preferably emitting focused ion beams, although non-focused beams maybe used in certain embodiments) that extends across the entire surface105 of the substrate in order to ion beam mill the surface 105 ofsubstrate 1. This ion beam milling shaves off or removes a portion ofthe surface of the glass substrate. For example, in certain embodimentsof this invention, the ion beam milling of step 101 removes from about2-100 angstroms (Å) (e.g., see depth “D” of shaved off glass in FIG. 2),more preferably from about 2-50 Å, even more preferably from about 4-20Å, and most preferably from about 6-12 Å of glass from the surface ofsubstrate 1.

Preferably, argon (Ar) ions are used to conduct the milling of substrate1 (i.e., Ar gas is used in the ion beam source to produce mostly Ar+ionsthat are directed toward the substrate surface to perform the milling)in step 101. Alternatively or additionally, other types of ions mayinstead be used (e.g., other inert gas ions such as Kr, Ne, and/or Xe)in the focused ion beam to perform the milling of substrate 1. Inert gasions are preferred so as to minimize potential reactions with thesubstrate 1. The ion beam milling is preferably performed in a vacuumchamber where the ion beam source(s) and the substrate 1 being milledare located. A pressure of from about 5.0×10⁻⁴ to 1.0×10⁻⁴ is preferablymaintained in this vacuum chamber where the substrate is located duringthe milling process. Additionally, each ion beam source is preferablyoperated during the ion beam milling process so that the beam has an ionenergy of from about 300 to 5,000 eV, more preferably from about 1,500to 2,000 eV, and most preferably from about 1,400 to 1,600 eV. One ormore ion beam sources may be used during the milling process as willmore fully described below.

FIG. 3 is a side cross sectional view of substrate 1 after step 101(i.e., after the substrate 1 has been ion beam milled in step 101). Ascan be seen from comparing FIG. 2 (substrate 1 before milling) with FIG.3 (substrate 1 after milling), the ion beam milling removes an amount“D” of glass from the surface of the substrate 1 and thereby smoothensthe surface of the substrate 1 so that a smoother surface 107 results.Moreover, it can be seen that the ion beam milling removes ofsubstantially reduces many of the nano-cracks 106 that were originallypresent at the surface of the substrate.

Referring back to FIG. 1, after the substrate 1 has been ion beam milledin such a manner, a coating system is deposited on smoothened surface107 of the substrate in step 102. For example, as will be explainedbelow with regard to FIGS. 6-20, a DLC inclusive layer/coating system 5be deposited on surface 107 in step 102. Additionaly or alternatively,any other type of suitable coating system or layer (e.g., low-E coatingsystem, or the like) may instead by deposited on surface 107 in step 102via ion beam deposition, sputter, or any other suitable depositionprocess.

Surprisingly, it has been found that the ion beam milling of thesubstrate 1 as described above prior to deposition of a DLC inclusivelayer or coating system (e.g., see coating system 5 in any of FIGS. 6-8)on the smoothened surface 107 of the substrate results in a more scratchresistant DLC inclusive layer or coating system than if such ion beammilling had not occurred. Moreover, it has been found that the ion beammilling also results in improved adherence of the layer or coatingsystem to surface 107 of substrate 1.

FIGS. 4(a) and 4(b) illustrate an ion beam milling apparatus provided ina vacuum chamber 110 according to an embodiment of this inventionconsistent with FIGS. 1-3. FIG. 4(a) is a side perspective view of theapparatus, while FIG. 4(b) is a top view of the apparatus. The ion beammilling apparatus includes conveyor 111 driven by at least one driveroll or gear 112 in order to move glass substrate(s) 1 through theapparatus in direction “F”. Glass substrate 1 is on conveyor 111, and ismoved through the apparatus in direction “F” so that the entire majorsurface 105 (including nano-cracks and surface roughness) of thesubstrate is passed under a plurality of ion beam sources 113-115. Thepreferably focused ion beams 34 (alternatively, beams 34 may benon-focused in certain embodiments) from ion beam sources 113, 114 and115 impinge upon surface 105 of substrate (e.g., using Ar+ions) therebymilling the same as discussed above. As discussed above, the ion beamsfunction to shave off a portion of the glass substrate 1 at the surfacethereof so that the result is a smoother substrate surface 107 havingfewer nano-cracks therein (see FIG. 3), on which a coating system 5 isto be deposited.

Ion beams 34 in FIG. 4(a) are shown hitting the surface 105 of substrate1 at an angle Ω of approximately 90 degrees. However, in otherembodiments, ion beams 34 may be directed at surface 105 so as toimpinge upon the same at angles of from about 30-90 degrees (e.g., fromabout 40-60 degrees) so as to achieve more of a shaving effect (i.e., sothat glass is more easily removed from the substrate by the ion beams).

FIGS. 4(a) and 4(b) illustrate the use of three separate fixed ion beamsources 113, 114, and 115, respectively, under which the substratepasses. The use of three fixed sources 113-115 under which the substrate1 passes results in three ion beam milling “scans” of the substrateduring the milling process. However, more or less than three ion beamsources may be used. For example, only 1 or 2 ion beam scans may beperformed on the substrate 1 in certain embodiments, while 4-10 ion beamscans may be performed on the substrate 1 in other embodiments. Also, inthe apparatus of FIG. 4 the linear ion beam sources 113-115 are fixed inplace so that a scan results when the entire surface of the substrate 1passes under the focused elongated beam 34 from the source. However, inalternative embodiments of this invention, a single linear ion beamsource may instead be used that is capable of moving back and forthacross a fixed substrate 1 (i.e., the number of ion beam “scans” of thesubstrate during the milling process is determined by the number oftimes the source moves back and/or forth across the substrate surface).For example, with a moving ion beam source and corresponding milling ionbeam 34, if the source moves back and forth two times (two completecycles of back and forth) across the entire surface of the substrate,then four ion beam scans have been carried out on the substrate 1.

FIG. 5(a) illustrates that a substrate 1 becomes smoother the more ionbeam milling scans that are performed on tempered soda-lime-silica glasssubstrates. “Rms” stands for root mean square airside surface roughnessof the substrate 1 surface 105, measured in nm in FIG. 5(a). Differentcurves are provided as a function of whether the SO₂ gas flow was on tocoat rollers in a tempering furnace. In certain embodiments of thisinvention, substrate 1 has a RMS surface roughness (nm) of from about1.5 to 3.0, and an average roughness (nm) of from about 1.0 to 2.5 priorto ion beam milling (these ranges are a function of characteristics suchas whether the substrate has been temper washed or not, whether it hasbeen coater washed, etc. However, after ion beam milling according to anembodiment of this invention, both the RMS surface roughness and theaverage surface roughness are reduced so that the surface roughnessafter ion beam milling is no more than about 90% of that before themilling, more preferably no more than about 80% of that before themilling, even more preferably no more than about 70% of that before themilling, and most preferably no more than about 60% of that before themilling. Chart A set forth below illustrates surface roughness valuesfor a temper washed soda-lime-silica glass substrate 1 that has beenwashed with RO (reverse osmosis) water and thermally tempered(circulating air flow in the tempering furnace was on) before being ionbeam milled, while Chart B below illustrates the surface roughnessvalues of the substrate after it has been ion beam milled according tothis invention. Chart B also includes an indication of how may ion beammilling scans were used. For sample #1, SO₂ flow was on while for sample#2 it was off.

CHART A (before ion beam milling) Substrate Sample Roughness (RMS)(nm)Roughness (Avg)(nm) #1 2.58 2.12 #2 1.48 1.19

CHRT B (after ion beam milling) Substrate Sample Scans Roughness(RMS)(nm) Roughness(Avg)(nm) #1  3 1.24 0.94 #1 12 0.99 0.72 #2  3 0.900.71 #2 12 0.93 0.67

As can be seen in Charts A and B, the ion beam milling results in asignificant smoothening of the substrate 1. After three ion beam scans,for example, sample #1's RMS surface roughness was reduced from 2.58 to1.24 (i.e., the RMS surface roughness value after the ion beam millingwas approximately 48% (1.24 divided by 2.58) of what it was prior to themilling). After twelve ion beam scans, sample #1's RMS surface roughnesswas reduced from 2.58 to 0.99 (i.e., the RMS surface roughness valueafter the ion beam milling was approximately 38% of what it was prior tothe milling).

FIGS. 5(b) and 5(c) illustrate experimental results for differentnumbers of ion beam milling scans across two different respectiveannealed soda-lime-silica glass substrates with DLC inclusive coatingsthereon, using 100 sccm Ar at 3,000 V. The coated articles tested inFIGS. 5(b) and 5(c) were coated, as shown in FIG. 6(d), with ahydrogenated DLC inclusive layer (ta-C:H) using acetylene gas in the ionbeam source used to deposit the DLC inclusive layer. Scratch resistance(SR) in FIGS. 5(b) and (c) is defined herein as a function of how muchpressure is needed to be applied to a ruby head (cylindrically shaped,2.5 mm diameter, 3 mm height) mounted on the head of a linear taberabraser system, in order to cause a scratch to be formed in the surfaceof the coated article when the ruby head is moved across said surface.The ruby crystal has a hardness of 9 on the MOHs scale. The coatedarticle (e.g., see FIG. 6(d)) is secured underneath the head and islinearly abraded at a given load. In the case of no scratch, the load isincreased and the head is placed at an adjacent area of the articlesurface. This process is continued until a scratch becomes visible. Ascratch herein is defined as being a visible mark seen at any azimuthalangle against a black surface. A light scratch is defined as beingvisible only at a normal angle to the article surface. Physically, ascratch implies the underlying glass 1 scratched with the thin DLCinclusive film/layer being punctured while with a light scratch thelayer is either partially removed or deformed. It is noted that normalglass 1 (with no DLC inclusive coating thereon) scratches given a loadof about 50-100 grams on the ruby head.

FIG. 5(b) relates to a single coated soda-lime-silica glass sheet, madefor use in a laminated windshield, while FIG. 5(c) relates to a singlecoated soda-lime-silica annealed glass sheet. As can be seen in bothFIG. 5(b) and FIG. 5(c), the scratch resistance (SR) goes up along withthe number of ion beam milling scans. For example, for both coatedarticles in FIGS. 5(b)-(c), when zero ion beam scans are performed(i.e., absent this invention), approximately 750 grams of pressure needsto be applied to the ruby head in order to cause scratches to be formedin the respective coated articles 1. However, after one ion beam scanacross the entire surface 105 of the substrate prior to deposition ofthe coating thereon, approximately 925 grams of pressure were needed onthe ruby head to form a scratch in the coated article of FIG. 5(b) andapproximately 1100 grams of pressure were needed on the ruby head toform a scratch in the coated article of FIG. 5(c).

Surprisingly, FIG. 5 illustrates significant SR improvement after 3 ionbeam milling scans of the substrate prior to deposition of the DLCinclusive layer. For example, in FIGS. 5(b) and (c) approximately 6,100grams of pressure were needed on the ruby head to form a scratch in thecoated articles when four scans were used. This, of course, is asignificant improvement over the 750 grams needed to form a scratchabsent this invention. Thus, in preferred embodiments of this invention,ion beam milling as shown in FIGS. 1-4 is performed in a manner so as toincrease scratch resistance (as defined regarding FIGS. 5(b) and 5(c))of the resulting coated article by at least a factor of 2, morepreferably by at least a factor of 3 as shown in FIGS. 5(b) and 5(c).

Another surprising result attributed to the aforesaid ion beam milling(e.g., 100 sccm Ar, at 3,000 V) of substrate 1 is that the amount ofsodium (Na) at the surface of the substrate is reduced as a result ofthe milling. This Na reduction at the surface means that the resultingcoated article will be less susceptible to Na-induced corrosion. Chart Cset forth below illustrates amounts of certain elements in the first 75angstroms (Å) of glass substrate 1 adjacent surface 105 prior to ionbeam milling according to this invention, and Chart D illustratesamounts of those same elements in the first 75 Å of glass substrate 1adjacent surface 107 after ion beam milling according to an embodimentof this invention, where about 7-10 Å of glass were shaved off duringthe milling process. Substrate sample #s 1 and 2 are subject to the samecharacteristics as in Charts A and B above. The values set forth inCharts C and D are in terms of atomic percentage (note: certain smallamounts of Ti and/or B are not shown in the charts).

CHART C (before ion beam milling) Substrate Sample Na O Sn Ca C S Si #113.5 59 0.5 1.3 3.6 5.7 16 #2 12.5 60 0.52 1.3 3.5 5.0 17

CHART D (after ion beam milling) Substrate Sample # scans Na Q Sn Ca C SSi Fe Ar #1 3 11 60 0.32 1.1 3.6 2 15.6 4.3 0.7 #1 12 6.6 57 0.1 2.3 70.3 16.2 6.6 1.2 #2 3 9.7 60 0.2 1.0 3.2 1.3 17.5 3.7 0.7 #2 12 5.3 570.1 2.7 6.5 — 17.5 6.6 1.3

As can be seen in Charts C and D above, the ion beam milling reduces theamounts of Na and sulfur (S) at the surface of the substrate, and tendsto increase the amount of iron (Fe) and/or argon (Ar) at the surface ofthe substrate. After three ion beam scans, for example, sample #1'ssodium (Na) content was reduced from 13.5 to 11 (i.e., the Na atomicpercentage content in the 75 angstroms adjacent the surface of thesubstrate after the ion beam milling was approximately 81% of what itwas prior to the milling. After twelve ion beam scans, sample #1's Nacontent in the 75 angstroms adjacent the surface of the substrate wasreduced from 13.5 to 6.6 (i.e., the Na atomic percentage content in the75 angstroms adjacent the surface 107 of the substrate after ion beammilling was approximately 49% of what it was prior to the milling).Thus, in certain embodiments of this invention, the Na content in the 20or 75 angstroms of the substrate adjacent surface 107 after ion beammilling is preferably less than about 85% of what it was before the ionbeam milling, more preferably less than about 75% of what it was beforethe ion beam milling. In a similar manner, in certain embodiments ofthis invention, the S content in the 20 or 75 angstroms of the substrateadjacent surface 107 after ion beam milling is preferably less thanabout 50% of what it was before the ion beam milling, more preferablyless than about 40% of what it was before the ion beam milling.

After substrate 1 has been ion beam milled as discussed above regardingFIGS. 1-5, any type of layer or coating system can be deposited (e.g.,ion beam deposited or sputtered) on the smoothened surface 107 of thesubstrate 1. Substrate 1 may either be at room temperature or heatedwhen a coating system is formed thereon according to differentembodiments of this invention. FIGS. 6-8 illustrate various DLCinclusive coating systems that may be at least partially ion beamdeposited on surface 107 of substrate 1 according to differentembodiments of this invention.

FIGS. 6(a) and 6(b) are side cross sectional views of a coated articleaccording to an embodiment of this invention, wherein a diamond-likecarbon (DLC) and fluoro-alkyl silane (FAS) inclusive coating system 5including layers 2, 3, 4 and 6 is provided on ion beam smoothenedsurface 107 of substrate 1. Substrate 1 may be of glass, plastic,ceramic, or the like. However, substrate 1 is preferably glass (e.g.,soda-lime-silica glass). FIG. 6(a) illustrates exemplary gases (e.g.,HMDSO and C₂H₂ (acetylene)) which may be used in the deposition oflayers 2-4, while FIG. 6(b) illustrates the resulting coated articleincluding the final resulting layers 2-4, 6 provided on substrate 1.

DLC inclusive layer 3 (e.g., having an index of refraction “n” ofapproximately 1.9 to 2.2, most preferably about 2.0) is provided on thesubstrate 1 for scratch resistance and/or durability (e.g., mechanicaland/or chemical durability) purposes in order to protect the underlyingsubstrate 1 from scratches, corrosion, and the like. Anti-reflectiveindex matching layer 2 is located between substrate 1 and DLC inclusivelayer 3 in order to couple or approximately match the respective indicesof refraction of DLC inclusive layer 3 and substrate 1. Anit-reflectivelayer 2 serves the purposes of enabling visible light reflectance off ofthe article to be reduced, thereby improving transmittance of the coatedarticle. Layer 2 may be located directly between DLC inclusive layer 3and substrate 1 so as to contact both of them in certain embodiments, oralternatively other layer(s) may be located between index matching layer2 and one/both of substrate 1 and layer 3. Anti-reflective layer 2 maybe referred to herein as an “index matching” layer when it has an indexof refraction “n” of a value between the respective indices “n” ofsubstrate 1 and layer 3.

Thus, the term “between” as used herein simply means that a primarylayer being referred to is located at some position between two otherlayers regardless of whether they are in direct contact (i.e., otherlayer(s) may also be located between the other layers, in addition tothe primary layer). For example, if a first layer is referred to hereinas being located “between” second and third layers, then the first layermay or may not be in direct contact with the second and third layers(e.g., fourth and fifth layers may be located between the first andthird layers). Likewise, the term “on” herein means both directly on andindirectly on. For example, if a first layer is “on” a substrate herein,the first layer may be directly on (contacting) the substrate oralternatively additional layer(s) may be located between the first layerand the substrate.

Layers 4 and 6 are optional and need not be provided in all embodimentsof this invention. When provided, primer layer 4 serves to improvebonding between FAS inclusive hydrophobic layer 6 and DLC inclusivelayer 3. FAS inclusive layer is provided for hydrophobic purposes,although hydrophobicity may be achieved absent FAS inclusive layer 6 incertain embodiments of this invention. As layers 4 and 6 are optional,coating system 5 may be made up of, for example, (i) layers 2, 3 only,(ii) layers 2-4 only, (iii) layers 2, 3 and 6 only, (iv) layers 2, 3, 4and 6 only, (v) layers 2, 3, 4 and 6 with other non-illustrated layer(s)overlying the same, underlying the same, or intermingled within orbetween any of layers 2, 3, 4 and/or 6, (vi) layers 2 and 3 along withother non-illustrated layers, (vii) layers 2-4 along with othernon-illustrated layers, (viii) layer 2 only, (ix) layer 3 only, and soon. The point here is that other layers may be provided on substrate 1(other than those illustrated in FIGS. 6(a) and 6(b)) according todifferent embodiments of this invention.

Starting from the substrate moving outwardly, anti-reflective layer 2 isfirst deposited on ion beam milled substrate 1. Layer 2 may be depositeddirectly on surface 107 of substrate 1 (preferable) so as to contactsame, or instead other layer(s) may be located between layer 2 andsubstrate 1. In any event, layer 2 may be referred to herein as an“index matching” layer. This phrase “index matching” (or “indexcoupling”) means that layer 2 has an index of refraction “n” having avalue that is between the respective indices of refraction “n” values ofsubstrate 1 and DLC inclusive layer 3, in order to reduce visible lightreflections off of the resulting coated article.

Anti-reflective layer 2 is preferably deposited on substrate 1 utilizingat least a siloxane gas, such as hexamethyldisiloxane (HMDSO) gas, viaan ion beam deposition process. It is noted that oxygen (O), argon (Ar)and/or other gas(es) may also be used in combination with the siloxane(e.g., HMDSO) in forming layer 2. When HMDSO [see FIG. 14] is usedduring the deposition process for layer 2, either alone or incombination with other gas(es), the resulting layer 2 includes DLC andmay be referred to as a DLC inclusive layer that is a hybrid amorphousmixture of DLC and SiO_(x) that includes sp³ carbon—carbon (C—C) bonds,silicon-oxygen (Si—O) bonds, etc. In certain other embodiments of thisinvention, this type of anti-reflective layer 2 may instead be formedwhere the HMDSO [see FIG. 14] is replaced in the ion beam depositionprocess with another siloxane gas or oxygen inclusive organosiliconcompound gas such as but not limited to tetramethyldisiloxane (TMDSO)[see FIG. 19], octamethylcyclotetrasiloxane (OMCTSO) [see FIG. 18],tetraethoxylsilane (TEOS) [see FIG. 20], any other suitable siloxane,any other suitable ethoxy substituted silane, any other alkoxysubstituted silane, any other oxygen inclusive organosilicon compoundinclusive gas, or any combination or mixture thereof, etc. Again, theseother gas(es) may be used either alone or in combination with othergas(es) such as oxygen (O) and/or argon (Ar) to form layer 2 via an ionbeam deposition or any other suitable process. Other than the O and Argases mentioned above, each of these gases is considered one or both ofa siloxane gas or an oxygen inclusive organosilicon compound gas, aswill be appreciated by those skilled in the art.

By using the aforesaid gas(es) during the formation of anti-reflectiveindex coupling layer 2, the resulting layer 2 even when including DLC isnot as hard as DLC inclusive layer 3 because layer 2 preferably has alesser amount/percentage of sp³ carbon—carbon (C—C) bonds than doeslayer 3. Moreover, the aforesaid gases enable a DLC inclusive layer 2 tobe formed that has an index of refraction “n” that is from about 1.4 to2.0, more preferably from about 1.5 to 1.8, thereby enabling layer 2 tofunction in an index coupling manner so as to reduce visiblereflections. It is also noted that layer 2 also functions as a primerlayer to improve bonding between a glass substrate 1 and DLC inclusivelayer 3. Because there is more Si in layer 2 than in layer 3, layer 2tends to bond better to substrate 1 than would layer 3 and layer 3 tendsto bond better to layer 2 than it would to the substrate 1 (seediscussion of TMS layer in parent application(s), incorporated herein byreference). In still further embodiments of this invention, TMS gas (seeFIG. 16), 3MS gas (see FIG. 17), DMS gas (see FIG. 15), and/or any othersuitable gas may be used instead of or in combination with HMDSO in theion beam deposition of layer 2 on substrate 1.

DLC inclusive layer 3 preferably includes at least some amount of DLC inthe form of highly tetrahedral amorphous carbon (ta-C) (i.e., includingsp³ carbon—carbon (C—C) bonds), in order to enhance the durabilityand/or scratch resistance of the coated article. In certain embodiments,one or both of layers 2 and 4 may also include at least some amount ofhighly tetrahedral amorphous carbon (ta-C), although typically not asmuch as is present in layer 3 so that layer 3 is harder than layers 2and 4. Thus, DLC inclusive layer 3 preferably has a greater percentageper unit area of highly tetrahedral amorphous carbon (ta-C) than doeither of layers 2 and 4. Highly tetrahedral amorphous carbon (ta-C)forms sp³ carbon—carbon (C—C) bonds, and is a special form ofdiamond-like carbon (DLC). The ta-C may be hydrogenated (i.e., ta-C:H)in certain embodiments of this invention.

DLC inclusive layer 3 may be formed and deposited on substrate 1 in anymanner described for depositing a DLC inclusive layer described in anyof the parent applications Ser. Nos. 09/617,815, 09/303,548, 09/442,805,or 09/583,862, all of which are incorporated herein by reference.Preferably DLC inclusive layer 3 is deposited on substrate 1 and layer 2via an ion beam deposition process using at least a hydrocarbon gas suchas C₂H₂ (acetylene). Other gas(es) such as oxygen and/or argon may beused in combination with acetylene during this deposition process. Inother embodiments of this invention, acetylene gas may be replaced orcomplimented with e.g., any other suitable hydrocarbon gas for use in oradjacent the ion beam source during the deposition of DLC inclusivelayer 3. The use of, for example, acetylene gas results in a DLCinclusive layer 3 that has more sp³ carbon—carbon (C—C) bonds than doeither of layers 2 and 4. Thus, layer 3 is harder than layers 2 and 4and functions to improve the durability (e.g., scratch resistance and/orchemical resistance) of the resulting coated article.

Optionally, at least a surface of substrate 1 (and optionally the entiresubstrate 1) may be heated to from 100-400 degrees C. when first DLCinclusive layer 2 is ion beam deposited thereon. Substrate 1 may or maynot be maintained at this temperature when additional DLC inclusivelayer(s) are deposited on the substrate following layer 2. For example,in certain embodiments, an IR heater(s) may continue to heat substrate 1when additional DLC inclusive layers 3, 4 are deposited. Alternatively,no heat need be applied to substrate 1 when layers 2-4 are beingdeposited, and heat retained from a step B prior heating may be utilizedto achieve results discussed herein regarding improved durability,higher density, and/or more resistance to losing hydrophobiccharacteristics.

In embodiments where primer layer 4 is desired, layer 4 is deposited on(either directly or indirectly) DLC inclusive layer 3 (the substrate 1may or may not be heated as discussed above when primer layer 4 isdeposited). Oxide inclusive primer layer 4 preferably is deposited onlayer 3 utilizing at least a siloxane gas such as hexamethyldisiloxane(HMDSO) gas via an ion beam deposition process. It is noted that oxygen(O), argon (Ar) and/or other gas(es) may also be used in combinationwith the HMDSO [see FIG. 14] in forming layer 4. When HMDSO is usedduring the deposition process for primer layer 4, either alone or incombination with other gas(es), the resulting primer layer 4 includesDLC, and may be referred to as a DLC inclusive layer that is a hybridamorphous mixture of DLC and SiO_(x) that includes sp³ carbon—carbon(C—C) bonds, silicon-oxygen (Si—O) bonds, etc. In certain otherembodiments of this invention, this type of primer layer 4 may insteadbe formed where the HMDSO is replaced in the deposition process withanother siloxane gas or an oxygen inclusive organosilicon compound gassuch as but not limited to tetramethyldisiloxane (TMDSO) [see FIG. 19],octamethylcyclotetrasiloxane (OMCTSO) [see FIG. 18], tetraethoxylsilane(TEOS) [see FIG. 20], any other suitable siloxane, any other suitableethoxy substituted silane, any other alkoxy substituted silane, anyother oxygen inclusive organosilicon compound inclusive gas, anycombination or mixture thereof, etc. Again, these other gas(es) may beused either alone or in combination with other gas(es) such as oxygenand/or argon to form primer layer 4 via an ion beam deposition process.Each of these gases (other than O and Ar) is considered one or both of asiloxane gas or an oxygen inclusive organosilicon compound gas, as willbe appreciated by those skilled in the art.

By using these gases during the formation of primer layer 4, theresulting layer 4 even when including DLC is not as hard as DLCinclusive layer 3 because layer 4 preferably has a lesseramount/percentage of sp³ carbon—carbon (C—C) bonds than does layer 3.Purposes of primer layer 4 include improving bonding between FASinclusive layer 6 and DLC inclusive layer 3, and improving durability ofthe overall coating system. As for improving the bonding characteristicsof FAS inclusive layer 6 to DLC inclusive layer 3, it is believed thatFAS will not bond extremely well to carbon itself in layer 3, but willbond to materials such as silicon oxide which is in primer layer 4.Thus, the Si, C, and/or O in primer layer 4 enables layer 4 to be bothdurable (due to the DLC in layer 4) as well as improve bonding betweenlayers 6 and 3 (due to the C, Si and/or O in layer 4). For example, DLCinclusive layer 3 bonds well to the C and/or Si in primer layer 4, whilethe FAS inclusive layer 6 bonds well to the Si and/or O in primer layer4.

In other embodiments of this invention, primer layer 4 need not includeDLC and instead may be made of or include any of titanium oxide(TiO_(x)), silicon oxide (SiO_(x)), VO_(x), HfO_(x), any mixturethereof, or any other suitable material such as another oxide layer. Instill further embodiments of this invention, any of the aforesaid oxidesmay be mixed with a DLC inclusive material (e.g., deposited via HMDSO orany of the other gases discussed above) to form primer layer 4.

When a hydrophobic coating is desired, this may be achieved in anymanner described in any of the parent application(s), all incorporatedherein by reference. Layer 6 may or may not be needed in hydrophobicembodiments depending upon the manner in which hydrophobicity isachieved. Where fluoro-alkyl silane (FAS) compound inclusive layer 6 isdesired, it may be applied on substrate 1 over layers 2, 3 and 4 asshown in FIGS. 6(a) and 6(b). Due at least to hydrophobic layer 6, theresulting coating system 5 can function in a hydrophobic manner (i.e.,it is characterized by high water contact angles θ and/or low surfaceenergies as described below), and optionally may be characterized by lowtilt angle(s) β in certain embodiments. In general, the DLC inclusivelayer(s) 2, 3 and/or 4 provide durability, hydrophobicity and priming,while FAS inclusive layer 6 functions to even further increase thecontact angle θ of the coating system 5.

It is surmised that the surface of DLC inclusive primer layer 4 (orlayer 3 when primer layer 4 is not present in certain embodiments)includes highly reactive dangling bonds immediately after itsformation/deposition, and that the application of FAS inclusive layer 6onto the surface of primer layer 4 shortly after layer 4's formationenables tight binding and/or anchoring of FAS inclusive layer 6 to thesurface of layer 4. This results in increased contact angle θ (improvedhydrophobicity) and a durable coating system 5. In certain embodimentsof this invention, it has been found that FAS inclusive layer 6 bondsmore completely to DLC inclusive primer layer 4 when FAS layer 6 isapplied on the upper surface of layer 4 within one hour or so afterlayer 4 is formed, more preferably within thirty minutes after layer 4is formed, and most preferably within twenty minutes after layer 4 isformed. As discussed in more detail below (see FIG. 13), at least FASinclusive layer 6 may be heated (thermally cured) after it has beendeposited on the substrate 1 in order to improve its durability incertain embodiments.

Overlying layer 6 may be substantially all FAS, or only partially FAS indifferent embodiments of this invention. Layer 6 preferably includes atleast one compound having an FAS group. Generally speaking, FAScompounds generally comprise silicon atoms bonded to four chemicalgroups. One or more of these groups contains fluorine and carbon atoms,and the remaining group(s) attached to the silicon atoms are typicallyalkyl (hydrocarbon), alkoxy (hydrocarbon attached to oxygen), or halide(e.g., chlorine) group(s). Exemplary types of FAS for use in layer 6include CF₃(CH₂)₂Si(OCH₃)₃ [i.e., 3, 3,3trifluoropropyl)trimethoxysilane]; CF₃(CF₂)₅(CH₂)₂Si(OCH₂CH₃)₃[i.e.,tridecafluoro-1,1,2,2-tetrahydrooctyl-1-triethoxysilane];CF₃(CH₂)₂SiCl₃; CF₃(CF₂)₅(CH₂)₂SiCl₃; CF₃(CF₂)₇(CH₂)₂Si(OCH₃)₃;CF₃(CF₂)₅(CH₂)₂Si(OCH₃)₃; CF₃(CF₂)₇(CH₂)₂SiCl₃; CF₃(CF₂)₇(CH₂)₂SiCH₃Cl₂;and/or CF₃(CF₂)₇(CH₂)₂SiCH₃(OCH₃)₂. These FAS material may be usedeither alone or in any suitable combination for layer 6. At leastpartial hydrolysate (hydrolysed) versions of any of these compounds mayalso be used. Moreover, it is noted that this list of exemplary FASmaterials is not intended to be limiting, as other FAS type materialsmay also be used in layer 6. While FAS inclusive layer 6 is applied overlayers 2-4 physical rubbing (or buffing) in certain preferredembodiments of this invention, layer 6 could instead be applied in anyother suitable manner in other embodiments of this invention. Moreover,according to alternative embodiments of this invention, a hydrophobictype layer 6 for increasing contact angle and thus hydrophobicity neednot include FAS. Other hydrophobic layers 6 could instead be used.

According to certain embodiments of this invention, while layers 2-4 mayeach include DLC, at least two of these three layers is/are preferablydeposited using different precursor or feedstock gases (e.g., a siloxanegas such as HMDSO or the like for layer(s) 2, 4 vs. a hydrocarbon gassuch as C₂H₂ or the like for layer 3) so that layer 3 has differentcharacteristics (e.g., different hardnesses and/or densities) thanlayer(s) 2 and/or 4. Layers 2 and 4 may have approximately the samecharacteristics in certain embodiments of this invention. Alternatively,layers 2 and 4 may also have different characteristics and be depositedwith different gases or gas (e.g., methane or hexane) combinations inother embodiments of this invention.

In an exemplary embodiment, anti-reflective index matching DLC inclusivelayer 2 may be deposited using a plasma ion beam deposition techniqueutilizing HMDSO gas and oxygen (O) gas (e.g., the oxygen gas may flowthrough the ion beam source itself while the HMDSO gas may be introducedinto the ion beam outside of the source itself between the slit and thesubstrate and/or in the source itself). Meanwhile, DLC inclusive layer 3may be deposited using an ion beam deposition technique utilizing a C₂H₂(acetylene) inclusive precursor or feedstock gas either alone or incombination with oxygen and/or argon. Still further, primer DLCinclusive layer 4 may be deposited using an ion beam depositiontechnique utilizing HMDSO gas and both argon (Ar) and oxygen (O) gas(e.g., the oxygen/argon gases may flow through the ion beam sourceitself while the HMDSO gas may be introduced into the ion beam outsideof the source itself between the slit and the substrate and/or in thesource itself). The addition of the Ar gas for use in depositing primerlayer 4 (Ar may not be used for layer 2) may cause layer 4 to have agreater hardness than layer 2, although layer 4 may still not be as hardas layer 3.

Additionally, it is believed that the underlying layer 2 (including DLC,Si and O) deposited using e.g., HMDSO functions as a barrier layer toprevent certain impurities from getting into or out of the substrate 1.Moreover, when HMDSO (see FIG. 14) is used in the deposition process oflayer 2, the Si in layer 2 helps to enable overlying DLC inclusive layer3 to better bond and/or adhere to a glass substrate 1 via layer 2.

Surprisingly, it has also been found that the use of layer 2 (e.g.,deposited via HMDSO or other siloxane gas) provides a morecontinuous/contiguous coating on a glass surface at very thinthicknesses as compared to a DLC inclusive layer 3 deposited using C₂H₂(acetylene) gas directly on glass. As a result, layer 2 can be depositedfirst directly on milled glass 1 at a relatively thin thickness, and theoverlying layer 3 need not be as thick as would otherwise be required.In general, the thinner the layer 3, the higher the transmission of theoverall coating system. Moreover, the provision of layer 2 may enableimproved yields to be achieved, as the occurrence of pinholes in thecoating system is less likely.

In embodiments such as where DLC inclusive layer 3 is formed on thesmoothened surface 107 of ion beam milled substrate 1 using a C₂H₂(acetylene) inclusive precursor or feedstock gas and DLC inclusivelayers 2 and/or 4 is/are formed on the milled substrate using at least aHMDSO (or other siloxane or oxygen inclusive organosilicon gas)inclusive precursor or feedstock gas, then layer(s) 2 and/or 4 tend tointermix with layer 3 during the deposition process. Thus, there may notbe a clear line(s) delineating or separating layers 2, 3 and 4 in thefinal product due to this intermixing (i.e., ion mixing) of the materialfrom the different layers. However, for purposes of simplicity, thelayers 2-4 are referred to and illustrated herein as separate layers dueto the different deposition processes (e.g., gases and/or energies) usedin respective formations of adjacent layers.

It has been found that the DLC inclusive layer 3 formed using ahydrocarbon gas, such as C₂H₂ (acetylene) inclusive precursor orfeedstock, tends to have a greater hardness and density than do layers 2and 4 formed e.g., using at least a siloxane such as HMDSO inclusiveprecursor or feedstock gas. For example, in certain exemplaryembodiments of this invention, layer 3 may have an average hardness(measured via a nano-indentation hardness measuring technique) of fromabout 45-85 GPa, more preferably from about 50-70 GPa, and mostpreferably from about 55-60 GPa. Meanwhile, when formed via HMDSO orsome other siloxane, layer(s) 2 and 4 may have an average hardness(es)of from about 1-35 GPa, and more preferably from about 10-30 GPa. Usinga nano-indentation hardness measuring technique, the final coatingsystem 5, including e.g., layers 2-4 and 6, may have an average hardnessof at least about 10 GPa, more preferably from about 25-60 GPa, and evenmore preferably from about 30-45 GPa.

Thus, coating system 5 includes silicon (Si) and oxygen (O) and DLCinclusive layer 2 which functions as both an index matching/couplinglayer and to improve the bonding characteristics of harder DLC inclusivelayer 3 to the substrate. While the Si in layer 2 improves the bondingof layer 3 to substrate 1, it is preferred that less Si be provided inlayer 3 than in layer 2 because the provision of Si in a DLC inclusivelayer may result in decreased scratch resistance and/or decreasedhardness. Layer 3 may or may not include Si in different embodiments ofthis invention. While layer 2 allows for improved bonding to thesubstrate and reduced visible light reflections, the provision of DLCand some sp³ carbon—carbon bonds therein allows this layer 2 to haverather high hardness values so as to render the resulting product moredurable and thus resistant to scratching, abrasions, and the like.Because primer layer 4 may include DLC, Si and O in certain embodimentsas well, many of these same attributes apply to layer 4 as well.

In embodiments where substrate 1 is of or includes glass (e.g.,soda-lime-silica glass), anti-reflective layer 2 may be from about 10 to250 angstroms (A) thick, more preferably from about 10 to 150 angstromsthick, and most preferably from about 30-50 angstroms thick; DLCinclusive layer 3 may be from about 10 to 250 angstroms thick, morepreferably from about 10 to 150 angstroms thick, and most preferablyabout 30-60 angstroms (Å) thick, and primer layer 4 may be from about 10to 250 Å thick, more preferably from about 10 to 150 Å thick. FASinclusive layer 6 may be from about 5-80 angstroms (Å) thick, morepreferably from about 20-50 Å thick. However, these thicknesses are notlimiting and the layers may be of other appropriate thicknesses incertain embodiments of this invention. Moreover, in embodiments wheresubstrate 1 is of or includes plastic, layers 2, 3 and/or 6 may be ofgreater thickness(es) than those described above.

In certain embodiments, DLC inclusive layer 3 may have an approximatelyuniform distribution of sp³ carbon—carbon bonds throughout a largeportion of its thickness, so that much of the layer has approximatelythe same density. In such embodiments, layers 2 and/or 4 may include alesser percentage(s) of sp³ carbon—carbon bonds. As with layer 3, thedistribution of sp³ carbon—carbon bonds in layers 2 and 4 may beapproximately uniform through their respective thicknesses, oralternatively may vary. In layer 2 for example, the percentage or ratioof sp³ carbon—carbon bonds may increase throughout the thickness of thelayer 2 toward layer 3. Likewise, in layer 3 the percentage or ratio ofsp³ carbon—carbon bonds may be approximately uniform through the layer'sthickness or instead may gradually increase throughout the thickness ofthe layer 3 toward layer 4. It is noted that in DLC inclusive layer 3,at least about 40% (more preferably at least about 60%, and mostpreferably at least about 80%) of the carbon—carbon bonds in that layer3 are of the sp³ carbon—carbon type. In each of layers 2 and 4, at leastabout 5% (more preferably at least about 10%, and most preferably atleast about 20%) of the carbon—carbon bonds are of the sp³ carbon—carbontype. However, in layers 2 and 4 a lesser percentage of the total bondsin the entire layer(s) are sp³ carbon—carbon type bonds due to thepresence of, e.g., Si and O in these layers.

It is believed that the presence of sp³ carbon—carbon bonds in layers2-4 increases the density and hardness of the coating system, therebyenabling it to satisfactorily function in automotive environments.Moreover, it is believed that heating substrate 1 as described aboveand/or shown in FIG. 21, so that the substrate 1 is heated/hot when DLCinclusive layer(s) 2, 3 and/or 4 are deposited thereon, results in oneor more of layers 2-4 having increased density. Layers 2-4 may or maynot include sp² carbon—carbon bonds in different embodiments, althoughformation of sp² carbon—carbon bonds is likely in all of these layersand even preferred to some extent especially in layers 2 and 4.

When hydrophobicity is desired, in order to improve the hydrophobicnature of coating system 5 atoms in addition to carbon (C) may beprovided in at least layer 3 when layers 4 and 6 are not provided. Forexample, in certain embodiments of this invention when layer 3 is theoutermost layer, that layer 3 (taking the entire layer thickness, oronly a thin 10 A thick layer portion thereof into consideration) mayinclude in addition to the carbon atoms of the sp³ carbon—carbon bonds,by atomic percentage, from about 0-20% Si (more preferably from about0-10%), from about 0-20% oxygen (O) (more preferably from about 0-15%),and from about 5-60% hydrogen (H) (more preferably from about 5-35% H).Optionally, in such embodiments layer 3 may include from about 0-10%(atomic percentage) fluorine (F) (more preferably from about 0-5% F) inorder to further enhance hydrophobic characteristics of the coating.This is discussed in more detail in one or more of the parent cases,incorporated herein by reference. In general, the provision of H inlayer 3 reduces the number of polar bonds at the coating's surface,thereby improving the coating system's hydrophobic properties. Thesematerial(s) may or may not be provided in layer 3 when a hydrophobiccoating system is not desired, or when layers 4 and 6 are provided inthe system.

FIG. 6(c) is a side cross sectional view of a coated article accordingto another embodiment of this invention, the coated article includingion beam milled substrate 1 and layers 2 and 3 thereon. This FIG. 6(c)embodiment is similar to the FIG. 6(a)-6(b) embodiment, except thatlayers 4 and 6 are not provided in this embodiment. Thus, for example,the coated article may include milled substrate 1 (e.g., glass) on whichlayer 2 (e.g., formed using a HMDSO, or other siloxane or oxygeninclusive organosilicon gas) and DLC inclusive layer 3 (e.g., formedusing C₂H₂ gas) are formed. This coated article may or may not behydrophobic in different embodiments of this invention, althoughhydrophobic is preferred.

FIG. 6(d) illustrates a coated article according to another embodimentof this invention. This FIG. 6(d) embodiment is similar to the FIGS.6(a)-6(b) embodiment, except that layers 2, 4 and 6 are not provided inthis embodiment. Thus, for example, the coated article may include ionbeam milled substrate 1 (e.g., glass) on which DLC inclusive layer 3(e.g., formed using C₂H₂ gas) is formed. Any additional layers aremerely optional. Layer 3 may be doped with H or the like in versions ofthis embodiment to increase contact angle θ. Thus, as will all otherembodiments herein, coated articles according to this embodiment mayhave an initial contact angle θ of at least about 55 degrees (morepreferably of at least about 80 degrees, even more preferably of atleast about 100 degrees, and most preferably of at least about 110degrees).

FIG. 6(e) illustrates a coated article according to another embodimentof this invention. This FIG. 6(e) embodiment is the same as the FIG.6(d) embodiment described above, except that FAS inclusive layer 6 isalso provided on the ion beam milled substrate 1 over DLC inclusivelayer 3.

FIG. 7 is a side cross sectional view of a coated article according toanother embodiment of this invention, including ion beam milledsubstrate 1 (e.g. glass), DLC inclusive coating system 5 includinglayers 2, 3, 4 and 6 as described above with regard to the FIG. 6embodiment, and intermediate layer(s) 7 provided between layer 2 andsubstrate 1. Intermediate layer 7 may be of or include, for example, anyof silicon nitride, silicon oxide, an infrared (IR) reflecting layer orlayer system, an ultraviolet (UV) reflecting layer or layer system,another DLC inclusive layer(s), or any other type of desired layer(s).In this embodiment, it is noted that coating system 5 is still “on”substrate 1. The term “on” herein means that substrate 1 supports DLCcoating system 5, regardless of whether or not other layer(s) (e.g. 7)are provided therebetween (this also applies to the term “over” herein).Thus, coating system 5 may be provided directly on milled substrate 1 asshown in FIG. 1, or may be provided on milled substrate 1 with anothercoating system or layer 7 therebetween as shown in FIG. 7. Exemplarcoatings/layers that may be used as low-E or other coating(s)/layer(s) 7are shown and/or described in any of U.S. Pat. Nos. 5,837,108,5,800,933, 5,770,321, 5,557,462, 5,514,476, 5,425,861, 5,344,718,5,376,455, 5,298,048, 5,242,560, 5,229,194, 5,188,887 and 4,960,645,which are all hereby incorporated herein by reference.

FIG. 8 illustrates another embodiment of this invention that is the sameas the FIG. 6 embodiment, except that primer layer 4 is not provided. Ithas been found that primer layer 4 need not be provided in allembodiments of this invention. Likewise, in other embodiments of thisinvention (not shown), FAS inclusive layer 6 need not be provided. Instill further embodiments (not shown), one or more intermediate layer(s)7 may be provided between layer 2 and ion beam milled substrate 1 in theFIG. 8 embodiment.

Referring to the different embodiments of FIGS. 6-8, coating system 5 isat least about 60% transparent to or transmissive of visible light rays,more preferably at least about 70% transmissive, even more preferably atleast about 85% transmissive, and most preferably at least about 95%transmissive of visible light rays.

When substrate 1 is of glass, it may be from about 1.0 to 5.0 mm thick,preferably from about 2.3 to 4.8 mm thick, and most preferably fromabout 3.7 to 4.8 mm thick. In certain embodiments, another advantage ofcoating system 5 is that the ta-C (e.g., in layers 2-4) therein mayreduce the amount of soda (e.g., from a soda-lime-silica glass substrate1) that can reach the surface of the coated article and causestains/corrosion. In such embodiments, substrate 1 may besoda-lime-silica glass and include, on a weight basis, from about 60-80%SiO₂, from about 10-20% Na₂O, from about 0-16% CaO, from about 0-10%K₂O, from about 0-10% MgO, and from about 0-5% Al₂O₃. Iron and/or otheradditives may also be provided in the glass composition of the substrate1. In certain other embodiments, substrate 1 may be soda lime silicaglass including, on a weight basis, from about 66-75% SiO₂, from about10-20% Na₂O, from about 5-15% CaO, from about 0-5% MgO, from about 0-5%Al₂O₃, and from about 0-5% K₂O. Most preferably, substrate 1 is sodalime silica glass including, by weight, from about 70-74% SiO₂, fromabout 12-16% Na₂O, from about 7-12% CaO, from about 3.5 to 4.5% MgO,from about 0 to 2.0% Al₂O₃, from about 0-5% K₂O, and from about 0.08 to0.15% iron oxide. Soda lime silica glass according to any of the aboveembodiments may have a density of from about 150 to 160 pounds per cubicfoot (preferably about 156), an average short term bending strength offrom about 6,500 to 7,500 psi (preferably about 7,000 psi), a specificheat (0-100 degrees C.) of about 0.20 Btu/lbF, a softening point of fromabout 1330 to 1345 degrees F., a thermal conductivity of from about 0.52to 0.57 Btu/hrftF, and a coefficient of linear expansion (roomtemperature to 350 degrees C.) of from about 4.7 to 5.0×10⁻⁶ degrees F.Also, soda lime silica float glass available from Guardian IndustriesCorp., Auburn Hills, Mich., may be used as substrate 1, and then milledas discussed above regarding FIGS. 1-5. Any such aforesaid glasssubstrate 1 may be, for example, green, blue or grey in color whenappropriate colorant(s) are provided in the glass in certainembodiments.

In certain other embodiments of this invention, substrate 1 may be ofborosilicate glass, or of substantially transparent plastic, oralternatively of ceramic. In certain borosilicate embodiments, thesubstrate 1 may include from about 75-85% SiO₂, from about 0-5% Na₂O,from about 0 to 4% Al₂O₃, from about 0-5% K₂O, from about 8-15% B₂O₃,and from about 0-5% Li₂O.

In still further embodiments, an automotive window (e.g. windshield orside window) including any of the above glass substrates laminated to aplastic substrate may combine to make up substrate 1, with the coatingsystem(s) of any of the FIGS. 6-8 embodiments or any other embodimentherein provided on the outside or inside milled surface(s) of such awindow. In other embodiments, substrate 1 may include first and secondglass sheets of any of the above mentioned glass materials laminated toone another, for use in window (e.g. automotive windshield, residentialwindow, commercial architectural window, automotive side window, vacuumIG window, automotive backlight or back window, etc.) and other similarenvironments.

In hydrophobic embodiments of this invention, hydrophobic performance ofthe coating system of any of the FIGS. 6-8 embodiments is a function ofcontact angle θ, surface energy γ, tilt angle β, and/or wettability oradhesion energy W.

The surface energy γ of a coating system may be calculated by measuringits contact angle θ (contact angle θ is illustrated in FIGS. 9(a) and9(b)). FIG. 9(a) shows the contact angle of a drop on a substrate absentthis invention, while FIG. 9(b) shows the contact angle of a drop on asubstrate having a coating system thereon according to a hydrophobicembodiment of this invention. A sessile drop 31 of a liquid such aswater is placed on the coating as shown in FIG. 9(b). A contact angle θbetween the drop 31 and underlying coating system 5 appears, defining anangle depending upon the interface tension between the three phases inthe point of contact. Generally, the surface energy γ_(C) of a coatingsystem can be determined by the addition of a polar and a dispersivecomponent, as follows: γ_(C)=γ_(CP)+γ_(CD), where γ_(CP) is thecoating's polar component and γ_(CD) the coating's dispersive component.The polar component of the surface energy represents the interactions ofthe surface which is mainly based on dipoles, while the dispersivecomponent represents, for example, van der Waals forces, based uponelectronic interactions. Generally speaking, the lower the surfaceenergy γ_(C) of coating system 5, the more hydrophobic the coating andthe higher the contact angle θ.

Adhesion energy (or wettability) W can be understood as an interactionbetween polar with polar, and dispersive with dispersive forces, betweenthe coating system and a liquid thereon such as water. γ^(P) is theproduct of the polar aspects of liquid tension and coating/substratetension; while γ^(D) is the product of the dispersive forces of liquidtension and coating/substrate tension. In other words,γ^(P)=γ_(LP)*γ_(CP); and γ^(D)=γ_(LD)*γ_(CD); where γ_(LP) is the polaraspect of the liquid (e.g. water), γ_(CP) is the polar aspect of coatingsystem (e.g., coating system 5); γ_(LD) is the dispersive aspect ofliquid (e.g. water), and γ_(CD) is the dispersive aspect of the coatingsystem. It is noted that adhesion energy (or effective interactiveenergy) W, using the extended Fowkes equation, may be determined by:

W=[γ _(LP)*γ_(CP)]^(½)−[γ_(LD)*γ_(CD)]^(½)=γ₁(1+cos θ),

where γ₁ is liquid tension and θ is the contact angle. W of twomaterials is a measure of wettability indicative of how hydrophobic thecoating system is.

When analyzing the degree of hydrophobicity of outermost layer/portionof the coating system 5 with regard to water, it is noted that for waterγ_(LP) is 51 mN/m and γ_(LD) is 22 mN/m. In certain embodiments of thisinvention, the polar aspect γ_(CP) of surface energy of layers 3, 4and/or 6 is from about 0 to 0.2 (more preferably variable or tunablebetween 0 and 0.1) and the dispersive aspect γ_(CD) of the surfaceenergy of layers 3, 4 and/or 6 is from about 16-22 mN/m (more preferablyfrom about 16-20 mN/m). Using the above-listed numbers, according tocertain embodiments of this invention, the surface energy γ_(C) of layer6 (or 3 in certain embodiments) (and thus coating system 5) is less thanor equal to about 20.2 mN/m, more preferably less than or equal to about19.5 mN/m, and most preferably less than or equal to about 18.0 mN/m;and the adhesion energy W between water and the coating system is lessthan about 25 mN/m, more preferably less than about 23 mN/m, even morepreferably less than about 20 mN/m, and most preferably less than about19 mN/m. These low values of adhesion energy W and the coating system'ssurface energy γ_(C), and the high initial contact angles θ achievable,illustrate the improved hydrophobic nature of the coating systems 5according to different embodiments of this invention. While layers 3, 4and/or 6 functions to provide much of the hydrophobic nature of thecoating system 5, optional underlying DLC inclusive layer 2 improves thebonding characteristics of the coating system 5 to the substrate 1(e.g., glass substrate) and yet still provides adequate hardnesscharacteristics regarding the coating system 5 as a whole.

The initial contact angle θ of a conventional glass substrate 1 withsessile water drop 31 thereon is typically from about 22-24 degrees,although it may dip as low as 17 or so degrees in some circumstances, asillustrated in FIG. 9(a). Thus, conventional glass substrates are notparticularly hydrophobic in nature. In hydrophobic embodiments of thisinvention, the provision of coating system 5 on substrate 1 causes thecontact angle θ to increase to the angles discussed herein, as shown inFIG. 9(b) for example, thereby improving the hydrophobic nature of thearticle. As discussed in Table 1 of 09/303,548, the contact angle θ of ata-C DLC layer is typically less than 50 degrees, although it may behigher than that in certain circumstances as a function of ion energy.However, the makeup of DLC-inclusive coating system 5 described herein(with or without FAS inclusive layer 6) enables the initial contactangle θ of the system relative to a water drop (i.e. sessile drop 31 ofwater) to be increased in certain embodiments to at least about 55degrees, more preferably of at least about 80 degrees, even morepreferably to at least about 100 degrees, even more preferably at leastabout 110 degrees, and most preferably at least about 125 degrees,thereby improving the hydrophobic characteristics of the DLC-inclusivecoating system. An “initial” contact angle θ means prior to exposure toenvironmental conditions such as sun, rain, abrasions, humidity, etc. Asdiscussed above, heating of substrate 1 before and/or during ion beamdeposition of DLC inclusive layer(s) thereon can increase the resultingcoated article's resistance to diminishing contact angle upon exposureto UV radiation and/or friction such as wiper blades.

FIGS. 10-11 illustrate an exemplary linear or direct ion beam source 25which may be used to ion beam mill substrate 1 as shown and discussedwith regard to FIGS. 1-5, to deposit layers 2, 3 and 4 of coating system5, clean a substrate, or surface plasma treat a DLC inclusive coatingwith H and/or F according to different embodiments of this invention.Ion beam source 25 includes gas/power inlet 26, anode 27, groundedcathode magnet portion 28, magnet poles 29, and insulators 30. A 3 kV DCpower supply may be used for source 25 in some embodiments. Linearsource ion deposition allows for substantially uniform deposition oflayers 2-4 as to thickness and stoichiometry. The ion beam from thesource may be focused or non-focused in different embodiments of thisinvention. As mentioned above, FAS inclusive layer 6 is preferably notapplied using ion beam technology (rubbing/buffing is a preferreddeposition technique for layer 6), although it may be formed in such amanner in certain embodiments of this invention.

Ion beam source 25 is based upon a known gridless ion source design. Thelinear source is composed of a linear shell (which is the cathode andgrounded) inside of which lies a concentric anode (which is at apositive potential). This geometry of cathode-anode and magnetic field33 gives rise to a close drift condition. The anode layer ion source canalso work in a reactive mode (e.g. with oxygen and nitrogen). The sourceincludes a metal housing with a slit in a shape of a race track as shownin FIGS. 10-11. The hollow housing is at ground potential. The anodeelectrode is situated within the cathode body (though electricallyinsulated) and is positioned just below the slit. The anode can beconnected to a positive potential as high was 3,000 or more volts (V).Both electrodes may be water cooled in certain embodiments.Feedstock/precursor gases (e.g. Ar, acetylene, etc.), described herein,are fed through the cavity between the anode and cathode. The gas(es)used determines the make-up of the resulting layer deposited on anadjacent substrate 1, or the type of milling beam impinging upon thesubstrate.

The linear ion source also contains a labyrinth system that distributesthe precursor gas (e.g., TMS (i.e., (CH₃)₄Si or tetramethylsilane);acetylene (i.e., C₂H₂); 3MS (i.e., trimethyldisilane); DMS (i.e.,dichloro-dimethylsilane); hexane; methane; Ar; Kr; Xe; Ne; HMDSO (i.e.,hexamethyldisiloxane); TEOS (i.e., tetraethoxysilane), etc.) fairlyevenly along its length and which allows it to supersonically expandbetween the anode-cathode space internally. The electrical energy thencracks the gas to produce a plasma within the source. The ions (e.g.,Ar+ ions) are expelled out at energies in the order of eVc−a/2 when thevoltage is Vc−a. The ion beam emanating from the slit is approximatelyuniform in the longitudinal direction and has a Gaussian profile in thetransverse direction. Exemplary ions 34 are shown in FIG. 11. A sourceas long as one meter may be made, although sources of different lengthsare anticipated in different embodiments of this invention. Finally,electron layer 35 is shown in FIG. 11 completes the circuit therebyenabling the ion beam source to function properly.

In certain embodiments of this invention, gases discussed herein (e.g.,HMDSO, TEOS, acetylene, hexane, argon, methane, etc.) may be fed throughthe ion beam source via cavity 42 until they reach the area near slit 44where they are ionized. However, in other embodiments of this inventiondescribed above, a gas such as HMDSO (e.g., for layers 2 and 4) may beinjected into the ion beam at location 39 between the slit and thesubstrate 1, while gas such as oxygen and/or argon is caused to flowthrough cavity 42 in the source itself adjacent the ion emitting slit44. Alternatively, gases such as HMDSO, TEOS, etc. may be injected intothe ion beam both at 39 and via cavity 42.

In alternative embodiments of this invention, an ion beam source deviceor apparatus as described and shown in FIGS. 1-3 of U.S. Pat. No.6,002,208 (hereby incorporated herein by reference in its entirety) maybe used to deposit/form DLC inclusive layers 2-4 on milled substrate 1in accordance with any of the FIGS. 6-8 embodiments of this invention.One or multiple such ion beam source devices may be used (e.g., onesource may deposit all layers 2-4, or alternatively a different sourcemay be used for each of layers 2-4). In certain embodiments, another ionbeam source may be provided for initially cleaning the surface ofsubstrate 1 prior to deposition of layers 2-4. After layers 2-4 aredeposited, FAS inclusive layer 6 is preferably applied or depositedthereon.

Referring to FIG. 12, tilt angle β characteristics associated withcertain embodiments of this invention will be explained. In ahydrophobic coating, it is often desirable in certain embodiments tohave a high contact angle θ (see FIG. 9(b)) in combination with a lowtilt angle β. As shown in FIG. 12, tilt angle β is the angle relative tothe horizontal 43 that the coated article must be tilted before a 30 μL(volume) drop 41 (e.g., of water) thereon begins to flow down the slantat room temperature without significant trail. A low tilt angle meansthat water and/or other liquids may be easily removed from the coatedarticle upon tilting the same or even in high wind conditions. Incertain embodiments of this invention, coated articles herein have aninitial tilt angle β of no greater than about 30 degrees, morepreferably no greater than about 20 degrees, and even more preferably nogreater than about 10 degrees. In certain embodiments, the tilt angledoes not significantly increase over time upon exposure to theenvironment and the like, while in other embodiments it may increase tosome degree over time.

FIG. 21 illustrates steps taken in the manufacture of a coated articleaccording to an exemplary embodiment of this invention where the ionbeam milled substrate is heated before and/or when the coating system isdeposited thereon. First, an ion beam milled glass substrate (e.g.,soda-lime-silica glass) 1 is provided upon which a coating system is tobe deposited (step A). The glass substrate 1 is then heated (e.g., by anIR heater(s)) just prior to a DLC inclusive layer being deposited on thesubstrate (step B). Preferably, substrate 1 is heated to a temperatureof from about 100 to 400 degrees C. (more preferably from about 200-350degrees C.) by an infrared (IR) heater just prior to application of theDLC inclusive layer(s). A single IR heater may be located so as todirect IR radiation onto only the surface of the substrate I on whichthe DLC inclusive layer(s) is/are to be deposited. Alternatively, aplurality of IR heaters may be located so as to heat substantially theentire substrate to such temperature(s). Such heating of the substratemay be done after the substrate has been ion beam milled but before thecoating system is deposited thereon. In other embodiments, such heatingmay be done before and/or during the ion beam milling and/or during thedeposition of the coating system on the substrate. As can be seen fromthe above, regardless of which embodiment is adopted, milled substrate 1(only a surface thereof, or the entire substrate) is at a temperature offrom about 100-400 degrees C. (more preferably of from about 200-350degrees C.) at the time when a DLC inclusive layer(s) is depositedthereon. In step C, at least one DLC inclusive layer (e.g., see layers2-4 in FIGS. 6(a) through 6(e)) is then deposited on the heatedsubstrate via an ion beam deposition process to be more fully describedbelow. This heating of the substrate 1 can be applied an used inconjunction with any and/or all embodiments of this invention shownand/or described with respect to FIGS. 1-15.

Referring to FIGS. 1-11, and 21 an exemplary method of making a coatedarticle according to an exemplary embodiment of this invention will nowbe described. This method is for purposes of example only, and is notintended to be limiting.

Prior to coating system 5 being formed on glass substrate 1, the topsurface of a soda-lime-silica glass substrate 1 may be cleaned by way ofa first linear or direct ion beam source. Then, the surface 105 ofsubstrate 1 may be ion beam milled as shown and described in FIGS. 1-5so that at least 3 fixed linear focused ion beam scans are carried outover the entire surface of substrate 1 in order to smoothen out same andform surface 107 (alternatively, a single ion beam source may be movedback and forth across the substrate so as to make at least three passesover the substrate surface in order to mill the same; such embodimentwould only require one ion beam source for the milling). Ar gas may beused in the ion beam milling process. After ion beam milling using threeor more ion beam sources (see FIGS. 10-11) as shown in FIG. 4, thesubstrate 1 may optionally be heated to a temperature of from about100-400 degrees C. (see FIG. 21). A deposition process begins using alinear ion beam deposition technique via a source as shown in FIGS.10-11, or in FIGS. 1-3 of the '208 patent; with a conveyor having movedthe heated and/or milled substrate 1 from a heating and/or millingstation(s) to a position under the depositing source. This ion beamsource functions to deposit a DLC inclusive index matching layer 2 onmilled substrate 1, with at least HMDSO and oxygen being used as gas(es)fed through the source or inserted at 39. Because of the Si in the HMDSOgas used in the source, the resulting layer 2 formed on milled substrateincludes at least Si and O as well as DLC. The Si portion of DLCinclusive layer 2 enables good bonding of layer 2 to milled substrate 1(substrate 1 is glass in this example), and thus will also improve thebonding characteristics of layer 3 to the substrate via layer 2. The Oportion of layer 2 increases transmission and enables the refractiveindex “n” of layer 2 to be lowered so as to reduce visible lightreflections off of the final coated article.

After layer 2 has been formed, either the same or another ion beamsource is used to deposit layer 3 over (directly on in preferredembodiments) layer 2. Heating may or may not continue of the substrate 1during deposition of layer 3 thereon. To deposit overlying DLC inclusivelayer 3, another gas such as at least C₂H₂ is fed through the source (orinserted at location 39) so that the source expels the ions necessary toform layer 3 overlying layer 2 on substrate 1. The C₂H₂ gas may be usedalone, or in exemplary alternative embodiments the gas may be producedby bubbling a carrier gas (e.g. C₂H₂) through a precursor monomer (e.g.TMS or 3MS) held at about 70 degrees C. (well below the flashing point).Acetylene feedstock gas (C₂H₂) is used in certain embodiments fordepositing layer 3 to prevent or minimize/reduce polymerization (layer 2may or may not be polymerized in certain embodiments) and to obtain anappropriate energy to allow the ions to penetrate the surface on thesubstrate/layer 2 and subimplant therein, thereby causing layer 3 tointermix with layer 2 in at least an interface portion between thelayers. The actual gas flow may be controlled by a mass flow controller(MFC) which may be heated to about 70 degrees C. In certain optionalembodiments, oxygen (O₂) gas may be independently flowed through an MFC.The temperature of milled substrate 1 may be as discussed above; an arcpower of about 1000 W may be used; precursor gas flow may be about 25sccm; the base pressure may be about 10⁻⁶ Torr. The optimal ion energywindow for the majority of layers 2, 3 is from about 100-1,000 eV(preferably from about 100-400 eV) per carbon ion. At these energies,the carbon in the resulting layers 2, 3 emulates diamond, and sp³ C—Cbonds form. However, compressive stresses can develop in ta-C when beingdeposited at 100-150 eV. Such stress can reach as high as 10 GPa and canpotentially cause delamination from many substrates. It has been foundthat these stresses can be controlled and decreased by using an ionenergy during the deposition process in a range of from about 200-1,000eV. As stated above, layers 2 and 3 intermix with one another at theinterface between the two layers, thereby improving the bonding betweenthe layers. At particle energies (carbon energies) of several hundredeV, a considerable material transport can take place over several atomicdistances. This is caused by the penetration of fast ions and neutralsas well as by the recoil displacement of struck atoms. At sufficientlyhigh particle energies and impact rates, there is an enhanced diffusionof the thermally agitated atoms near the film surface that occurs viathe continuously produced vacancies. In the formation of ta-C:H, theseeffects can help improve film adhesion by broadening the interface(i.e., making it thicker, or making an interfacial layer between the twolayers 2 and 3 (or between layer 2 and glass 1) due to atom mixing).After layer 2 is deposited, the carbon from layer 3 implants into layer2 (i.e., subimplantation) so as to make the bond better of layer 3 tothe substrate. Thus, layers 2 and 3 are contiguous due to thisintermixing, and this “smearing” between the layers enhances theadhesion of layer 3 to both layer 2 and thus the substrate 1.

High stress is undesirable in the thin interfacing portion of layer 2that directly contacts the surface of a glass substrate 1 in the FIG. 6embodiment. Thus, for example, the first 1-40% thickness (preferably thefirst 1-20% and most preferably the first 5-10% thickness) of layer 2may optionally be deposited on substrate 1 using high anti-stress energylevels of from about 200-1,000 eV, preferably from about 400-500 eV.Then, after this initial interfacing layer portion of layer 2 has beengrown, the ion energy in the ion deposition process may be decreased(either quickly or gradually while deposition continues) to about100-200 eV, preferably from about 100-150 eV, to grow the remainder oflayer(s) 2 and/or layer(s) 3-4. Thus, in certain embodiments, because ofthe adjustment in ion energy and/or gases during the deposition process,DLC inclusive layers 2-4 may optionally have different densities anddifferent percentages of sp³ C—C bonds at different layer portionsthereof (the lower the ion energy, the more sp³ C—C bonds and the higherthe density).

While direct ion beam deposition techniques are preferred in certainembodiments, other methods of deposition may also be used in differentembodiments. For example, filtered cathodic vacuum arc ion beamtechniques may be used to deposit layers 2-4. Also, in certainembodiments, CH₄ may be used as a feedstock gas during the depositionprocess instead of or in combination with the aforesaid C₂H₂ gas.

After layers 2-3 have been deposited, primer layer 4 is deposited in amanner similar to that described above for layer 2. However, in oneparticular example, the gases used in forming layer 4 may include inaddition to the HMDSO and oxygen described above, argon (Ar) mixed withthe oxygen gas in order to enable more sp³ C—C bonds to be formed inlayer 4 than in layer 2 so that layer 4 is harder than layer 2 (fordurability purposes). The Ar/O mixture is preferably fed through thesource via cavity 42 while the HMDSO gas is preferably inserted into theion beam at 39, or alternatively may in addition or instead be caused toflow through the source at 42 along with the Ar/O gas mixture.

After DLC inclusive layers 2-4 have been formed on substrate 1, FASinclusive layer 6 is deposited thereon or applied thereto as shown inFIG. 6 (e.g., by rubbing or otherwise applying/depositing this layer 6in any other suitable manner).

After FAS inclusive layer 6 has been formed on the substrate 1, thecoated article may be again heated (e.g., at about 70-200 degrees C.this time). Surprisingly, as mentioned previously, it has been foundthat heating the coated article in such a manner after deposition oflayer 6 improves the durability of FAS inclusive layer 6, and thus ofthe overall coating system. It is thought that such hearing may “cure”layer 6 or otherwise cause it to more completely bond to itself and/orlayer 4.

FIG. 13 is a flowchart illustrating that according to certain optionalembodiments of this invention, FAS inclusive layers may be thermallycured after being deposited. A substrate 1 (e.g., glass, plastic, orceramic substrate) is provided at step 10, and then milled (see FIGS.1-5). At least one DLC inclusive layer 2-4 is deposited on the ion beammilled substrate at step 11. Following formation of the DLC inclusivelayer(s), an FAS compound inclusive layer is deposited on the substratein step 12. The FAS inclusive layer is preferably deposited directly onthe upper surface of a DLC inclusive layer or a primer layer in certainembodiments of this invention. After the DLC and FAS inclusive layershave been deposited on the substrate, the entire coated article (oralternatively only the FAS inclusive layer) is subjected to heating forcuring purposes in step 13. The heating may take place in any suitableoven or furnace, or alternatively may be implemented by an IR or anyother type of localized heating device. This heating may be at atemperature of from about 50 to 300 degrees C., more preferably at atemperature of from about 70 to 200 degrees C., and even more preferablyat a temperature of from about 70-100 degrees C. However, it is notedthat as the heating time goes up, the required temperature goes down.Thus, for purposes of example only, the heating may be conducted atabout 80 degrees C. for about 60 minutes (1 hour). Alternatively, theheating may be conducted at about 250 degrees C. for about 5 minutes, orat about 150 degrees C. for about 20 minutes. The time which the coatedarticle is subjected to heating after formation of layer 6 may rangefrom about 20 seconds to 2 hours in certain embodiments of thisinvention, more preferably from about one (1) minute to one (1) hour,depending on the temperature used. In preferred embodiments of thisinvention, at least the FAS inclusive layer (and preferably the entirecoated article) is heated at a temperature and for a period of timesufficient to achieve one or more of the durability and/or hydrophobicproperties discussed above.

As will be appreciated by those skilled in the art, coated articlesaccording to different embodiments of this invention may be utilized inthe context of automotive windshields, automotive side windows,automotive backlites (i.e., rear windows), architectural windows,residential windows, ceramic tiles, shower doors, and the like.

Once given the above disclosure, many other features, modifications, andimprovements will become apparent to the skilled artisan. Such otherfeatures, modifications, and improvements are, therefore, considered tobe a part of this invention, the scope of which is to be determined bythe following claims. For example and without limitation, certain coatedarticles according to this invention may be hydrophobic, other coatedarticles according to this invention may be hydrophilic, and still othercoated articles according to this invention may be neither hydrophobicnor hydrophilic.

What is claimed is:
 1. A method of making a coated article, the methodcomprising: providing a glass substrate; ion beam milling substantiallyan entire surface of the glass substrate so as to reduce the thicknessof the substrate by at least about 2 Å, wherein during the ion beammilling an ion beam is directed toward the glass substrate so as to hitthe substrate at an angle of from about 40-60 degrees in order to millthe substrate; and depositing a coating on the substrate over at least aportion of the ion beam milled surface thereof.
 2. The method of claim1, wherein said ion beam milling is performed so as to reduce thethickness of substantially the entire substrate by from about 4-20 Å. 3.The method of claim 1, wherein the ion beam milling is performed usingan ion energy of from about 1500-2000 eV.
 4. The method of claim 1,wherein said coating comprises diamond-like carbon.
 5. The method ofclaim 4, wherein said diamond-like carbon is deposited directly on theglass substrate so as to contact the glass substrate.
 6. The method ofclaim 4, wherein the diamond-like carbon is hydrogenated.
 7. The methodof claim 1, wherein said milling is performed to an extent so as toincrease scratch resistance of the coated article by at least a factorof two.
 8. A method of making a coated article, the method comprising:providing a glass substrate; ion beam milling substantially an entiresurface of the glass substrate so as to reduce the thickness of thesubstrate by at least about 4 Å; and depositing a coating on thesubstrate over at least a portion of the ion beam milled surfacethereof.
 9. The method of claim 8, wherein the ion beam milling isperformed using an ion energy of from about 1500-2000 eV.
 10. The methodof claim 8, wherein said coating comprises diamond-like carbon.
 11. Themethod of claim 10, wherein said diamond-like carbon is depositeddirectly on the glass substrate so as to contact the glass substrate.12. The method of claim 10, wherein the diamond-like carbon ishydrogenated.
 13. The method of claim 8, wherein said milling isperformed to an extent so as to increase scratch resistance of thecoated article by at least a factor of two.